The document provides an overview of acids, bases, and salts, detailing their properties, reactions, and importance in everyday life. It describes the pH scale, the formation of salts from different acid-base combinations, and various applications of substances like sodium hydroxide and baking soda. Additionally, it covers the water of crystallization and transformations between hydrated and anhydrous states of certain salts.

1. ACIDS, BASES AND SALTS

2. What are acids?
ACIDS are substances that form hydrogen ions (H+
(aq)) when
dissolved in water
Physical properties of Acids
 Acids taste sour (e.g. vinegar, lemon juice).
 Acids are harmful to living cells.
 Aqueous solutions of all acids contain hydrogen ions.
 Acid turns blue litmus red.
 Strong acids are corrosive

3. What are bases?
Bases are substances that form hydroxide(OH⁻)ions when
dissolved in water
Physical properties of bases:
 are taste bitter
 Strong bases are corrosive.
 Aqueous solutions of all bases contain
hydroxide ion.
 turns red litmus blue.
 Soapy/ slippery to touch.

4.  Litmus paper,Turmeric,
Red Cabbage and colored
petals of some flowers like
Petunia, Hydrangea and
Geranium are natural
indicators.
 Methyl Orange,
Phenolphthalein are
synthetic indicators.
 Substances whose odour
changes in acidic or basic
media such indicators are
called olfactory indicators.
Example:Vanilla, Onion
and Clove

5.  Reaction of acid with metals:
Acid + Metal → Salt + Hydrogen gas
HCl + Zn → ZnCl₂ + H₂
 Reaction of base with metals:
NaOH + Zn → Na₂ZnO₂ + H₂
(sodium zincate)

6.  Na₂CO₃ + HCl → NaCl + H₂O +CO₂
(Sodium carbonate)
 NaHCO₃ + HCl → NaCl + H₂O +CO₂
(sodium hydrogen carbonate)
 In the above reaction acids react with Metal Carbonates and
Metal Hydrogencarbonates to give salt, carbon dioxide and
water.
 Limestone, chalk and marble are different forms of calcium
carbonate.

7. Reaction between acids and
bases
 NaOH +HCl → NaCl + H₂O
 The reaction between a acid and base to give a salt
and water is known as a neutralisation reaction.

8. Reaction with metallic oxides
 In this reaction metallic oxides react with acids
to give salts and water.
 Metallic oxides are said to be basic oxides.
Reaction of a non- metallic oxide with
base
• In this reaction non- metallic oxides react
with a base to give salts and water.
•Non- metallic oxides are said to be acidic
oxides.

9.  Acids react with water to give hydronium ions(H₃O⁺) or H⁺
ion in water.
 Bases react water to give hydroxide (OH⁻) ions.
 Bases which are soluble in water are called alkalis.
 The reaction with acid or base with water is a highly
exothermic.
 Heat generated may cause the mixture to splash out and
cause burns.The glass container may also break due to
excessive heat.

10. ph scale
 Is a scale used to measure hydrogen ion concentration in a
solution.
 The p in the pH stands for ‘potenz’ in German meaning
power.
 Higher the hydronium ion concentration , lower is the pH
value.
 0 to 6 is acidic
 7 is neutral
 8 to 14 is alkaline/basic.
 pH paper changes color to
indicate a specific pH value

12.  Acids that give rise to
more hydronium ions
or hydrogen ions are
said to be strong acids.
 Acids that give rise to
less hydronium ions or
hydrogen ions are said
to be weak acids.
 Bases that give rise to
more hydroxide ions
are said to be strong
bases.
 Bases that give rise to
less hydroxide ions are
said to be weak bases.

13. Importance of pH in everyday life.
 Our body works within the pH of 7 to 7.8
 When pH of rain is less than 5.6 it is called acid
rain.
 Our stomach produces hydrochloric acid which
helps in digestion without harming our stomach.
 In case of indigestion our stomach produces
more acid and this causes pain and irritation. To
get rid of this we use bases called antacids..
These antacids neutralizes the excess acid.
 Magnesium hydroxide (milk of magnesia) is a
mild base.
 Tooth decay starts when the mouth pH is lower
than 5.5.
 Tooth enamel is made up of calcium phosphate

14.  Bee sting leaves an acid which causes pain and
irritation. Using a mild base like baking soda and
the area gives relief.
 Stinging hair of nettle leaves inject methanoic acid
causing burning pain.

16. How are salts formed:
Salts formed from:
 Strong acid + Strong base= are neutral with pH of 7
 Strong acid + Weak base= are acidic with pH value less
than 7
 Strong base + Weak acid= are basic with pH value
more than 7
 The combination of hydrochloric acid and sodium
hydroxide solution is called sodium chloride.
 Large crystals are often brownish due to impurities this
is called rock salt.

17. SODIUM HYDROXIDE:
When electricity is passed
through an aqueous solution of
sodium chloride( called brine).
It decomposes to form sodium
hydroxide. This process is
called the CHLOR-ALKALI
PROCESS because of the
products formed chlor for
chlorine and alkali for sodium
hydroxide.
NaCl + H₂O → NaOH +Cl₂ +H₂
Chlorine gas is given out at anode and
hydrogen gas and sodium
hydroxide is formed at cathode

18. BLEACHING POWDER
 It is formed by the action of
chlorine gas on dry slaked
lime (Ca(OH)₂)
 Bleaching powder is
represented as CaOCl₂
USES:
 For bleaching cotton and
linen in textile industries.
 For bleaching wood pulp in
paper factories.
 For bleaching washed
clothes in laundry.
 An oxidizing agent in many
chemical industries
 For disinfecting drinking
water to make it germ free.

19. BAKING SODA
 It is produced using sodium chloride
 The chemical name of the
compound is sodium
hydrogencarbonate ( NaHCO₃).
NaCl + H₂O + CO₂ +NH₃→ NH₄Cl
+NaHCO₃
USES
 Is used in soda – acid fire
extinguishers.
 Is also an ingredient in antacids.
 For making baking powder.

20. Preparation of baking powder:
 A mixture of baking soda along with a mild edible
acid such as tartaric acid.When baking powder is
heated or mixed with water carbon dioxide is
produced which cause bread or cake to rise making
them soft and spongy.
NaHCO₃ + H⁺ → CO₂ +H₂O+ sodium salt of acid

21. WASHING SODA
 The chemical name of washing
soda (Na₂CO₃.10H₂O)/ sodium
carbonate
 Recrystallisation of sodium
carbonate gives washing soda.
 It is a basic salt.
Uses:
 Used in glass, soap and paper
industries .
 Used in the manufacture of
sodium compound such as
borax.
 Used as cleaning agent for
domestic purpose.
 Used for removing permanent
hardness of water.

22. Are the crystals of salts dry:
 Copper sulphate crystals when heated lose water and
turn from blue to white.
 water of crystallization is the fixed number of water
molecules present in one formula unit of a salt.
 Chemicl formula of hydrated copper sulphate is
CuSO₄.5H₂O
 Gypsum chemical formula is CaSO₄.2H₂O

23.  On heating gypsum at 373 K,
it loses water molecule and
becomes calcium sulphate
hemihydrate (CaSO₄.½ H₂O)
this is called plaster of paris.
 On mixing again with water it
changes to gypsum.
uses:
 For making toys, materials
for decoration
 For making surfaces smooth.
 doctors use for supporting
fractured bones in the right
position